The present invention is concerned with a movable upper tool for a blank separating station situated in a machine for processing sheets to produce blanks for forming packages.
The creation of packages requires three successive steps. The first step is printing of a sheet with numerous motifs or prints, with every one being assigned to one package only. The second step is die-cutting of the sheet into several blanks, with each blank having only one printed motif. The third step or action is folding and gluing every blank so as to obtain a flattened package, which can be subsequently erected and filled with the contents.
After the die-cutting and in order to insure the whole cut sheet to be transferred, generally by means of a gripper bar which is mounted between two parallel extending chains, from the die-cutting station to a station for stripping the waste, which is disposed between the various blanks in the sheet and is not part of the final package, and then finally to a delivery station, all the blanks of the same sheet remain attached together by means of tiny linking points which correspond to tiny non-cutting slots or nicks which are made in the cutting rules of the press.
In the delivery station and according to the requirements, it should be possible to either form a pile of sheets with every one of the sheets having all of its blanks held together by the linking points or to form simultaneously several piles of blanks which have been separated from one another by breaking the linking points when running through a previous section called a blank-separation station.
The prior art blank separating stations use a movable upper tool and fixed lower tool. The upper tool consists of an assembly of blocks and the lower tool of a matrix plate with apertures. The movable blocks will press the blanks through the apertures of the lower matrix and, thus, break the various linking points which connect either the blanks to one another or the margin blanks to a peripheral waste portion of the sheet. The separating tools have to be adapted to the shape and to the layout of the blanks on every new run of sheets to be processed. Generally, the blocks are arranged in a full registry with regard to the cutting lines of the press on the lower side of a plate fitted to a movable upper tool-supporting frame of the blank separating station. A corresponding aperture or mesh of the lower matrix, which may consist of small bars, is situated underneath and opposite every block. The small bars are arranged in such a way as to overlap and form a grid or matrix of which the mesh has the dimensions of the blanks to be separated.
To avoid manufacture of new blank separating tools for every new run of sheets, U.S. Pat. No. 4,175,686, whose disclosure is incorporated herein by reference thereto and which is based on the same Swiss Application which resulted in Swiss Patent A 617,886, proposes to arrange the blocks for shiftable movement in a horizontal direction along bars fitted on a vertical movable frame. The fixed lower grid is composed of crossbars shiftable in such a way as to form a grid of which the meshes are of an adjustable dimension. Although these movable tools have already been simplified for quicker adjustability to a new sheet size, the fitting of the blocks on the inner side of the upper tool, as described in the above-mentioned U.S. Patent, has the drawback of requiring a relatively complex set-up means by the fact that a first stage necessitates the positioning of the blocks on the bars and the second one the interlocking and position of the tools which are to maintain the blocks on the bars. These operations require a rather lengthy time and are fastidious.
Another way of preparing the upper tool consists in gluing the blocks on the lower side of a plate. In such a case, a new upper tool is required for every new process having a sheet of blanks of different sizes or layout.